For centuries there have been windows with an outer frame and cross-pieces, called muntins, which separate individual panes of glass and are physically attached to them. Such muntins sometimes are called "true" muntins because they physically separate adjacent panes of glass. More recently, there have been windows with so-called "false" muntins or grids that are either glued or painted onto a large pane of glass to make it appear to be composed of smaller individual panes. Other expedients intended to provide the same visual effect have been grids extending across the inside of a large window pane and snapped in place in the outer frame of the window, and grids extending across the outside of a large window pane and attached to the outer frame by screws.